512 CRIMINAL JUSTICE AND BEHAVIOR
or unrelated PTP (e.g., Kerr, Niedermeier, & Kaplan, 1999; Kramer, Kerr, & Carroll, 1990;
Otto, Penrod, & Dexter, 1994; Ruva, McEvoy, & Bryant, 2007).
The majority of PTP tends to be negative or antidefendant (Dexter, Cutler, & Moran,
1992; Freedman & Burke, 1996; Imrich, Mullin, & Linz, 1995; Lieberman & Arndt, 2000;
Lieberman & Sales, 2006; Moran & Cutler, 1991). Positive or prodefendant PTP (P-PTP)
also exists, primarily in cases in which a defendant holds celebrity or high status in the
community (e.g., Martha Stewart, Michael Jackson, Kobe Bryant). Only a small amount of
research has explored the effects of P-PTP on juror decision making, and the results of this
research have been inconsistent. For example, Kovera (2002) examined how general (or
non-case-specific) PTP, having either a prodefense or proprosecution slant, affected juror
decisions. She found that those in the prodefense story condition required more evidence
to convict the defendant than did participants in the proprosecution or control condition.
However, that study did not find a significant difference between prodefense and propros-
ecution PTP on verdict decisions. Ruva and McEvoy (2008) sought to more directly
explore the effects of P-PTP on juror verdicts by using actual news stories related to the
trial that mock jurors viewed. They found that mock jurors exposed to P-PTP were signifi-
cantly less likely to render guilty verdicts than mock jurors in nonexposed and N-PTP con-
ditions. That study indicates that P-PTP can bias juror decision making and, like N-PTP,
makes it difficult for jurors to ignore extralegal information.
The courts have attempted to remedy the problem of juror bias associated with PTP
exposure in several ways (e.g., judicial instructions, careful voir dire, continuance, change
of venue; Steblay et al., 1999). These remedies are often ineffective, unavailable, or not
easily obtained by a defendant (Deitz & Sissman, 1984; Dexter et al., 1992; Kramer et al.,
1990; Moran & Cutler, 1991), resulting in prejudice against the defendant. However,
Bruschke and Loges (2004) suggested that these remedies may be effective in combination,
although not in isolation as predominantly studied.
The failure of judicial safeguards has been attributed to the courts’ assessment of jurors’
ability to disregard PTP if instructed to do so. These assessments are often based on judicial
“common sense” and reflect misconceptions of human information processing, memory,
and decision making (Studebaker & Penrod, 1997, p. 432). For example, a juror is defined
by the courts as being free from prejudice if he or she reports the ability to set aside opinion
and render a verdict based solely on the evidence presented in court (Imrich et al., 1995).
Although much research attests to jurors’ inability to do this (Steblay et al., 1999), both the
courts and PTP researchers have indicated that social scientists do not have an adequate
understanding of how PTP influences the thought processes of prospective jurors (Hope,
Memon, & McGeorge, 2004; Moran & Cutler, 1991; Studebaker & Penrod, 1997). Therefore,
more research exploring the mediational processes responsible for PTP’s biasing effects on
juror decision making is needed. With this purpose in mind, we investigated whether biased
impression formation (defendant credibility), emotion, and predecisional distortion are
possible mechanisms through which N-PTP and P-PTP impart their biasing effects on juror
decision making. In addition, we explored the relationship among these cognitive and emo-
tional factors and their relative contribution to PTP bias.
One possible explanation for how PTP influences verdict outcomes is that it affects
jurors’ impression of the defendant’s credibility. N-PTP has been shown to affect jurors’
perceptions of defendant credibility by causing them to form negative impressions of the